This nonprovisional application claims priority under 35 U.S.C. xc2xa7119(a) on Patent Application No. 2001-336712 filed in Japan on Nov. 1, 2001, the entirety of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a structure for supplying lubricating oil to a lubrication object in an internal combustion engine. The engine includes a generator having a stator with a generating coil and a rotor coupled to a crankshaft. The lubrication object is mounted on the crankshaft and is disposed opposite to the stator across the rotor in an axial direction. The lubrication object may, for example, be a one-way clutch for connecting a starter driven gear rotatably mounted on the crankshaft and the rotor of the generator which is coupled to the crankshaft.
2. Description of Related Art
One conventional lubricating oil supply structure of the above type for an internal combustion engine is disclosed in Japanese patent No. 2686595. The conventional lubricating oil supply structure has a free wheel doubling as the rotor of a generator and coupled to an end of a crankshaft. A free wheel gear has a bearing surface rotatably fitted over the crankshaft and positioned opposite to the stator of the generator axially across the free wheel. The free wheel gear is coupled to the free wheel by a one-way clutch. When the internal combustion engine starts to operate, the free wheel gear transmits rotational power from a starter motor to the free wheel and the crankshaft. To lubricate the bearing surface of the free wheel gear, a bearing near the free wheel of the input shaft of a transmission has an oil reservoir for being supplied with oil under pressure and a nozzle for ejecting oil in the oil reservoir toward the bearing surface. The bearing surface is lubricated with the oil ejected from the nozzle. With this structure, it is not necessary to define an oil hole for lubricating the bearing surface in the crankshaft, thus preventing the cost from increasing due to an increased number of steps for machining the crankshaft and also preventing the internal combustion engine from becoming larger in size due to an increased outside diameter of the crankshaft.
According to the above related art, the nozzle is defined in the bearing of the input shaft of the transmission. Accordingly, the bearing and the bearing surface of the free wheel gear are required to be positioned at such a distance over which the oil ejected from the nozzle reliably reaches the bearing surface. Furthermore, no member needs to be present in the ejected flow of oil between the input shaft and the crankshaft. The above requirements pose limitations on the layout of the free wheel gear and the bearing and also the layout of the generator and the transmission. Since the area of the bearing surface to which the ejected oil is applied depends on the layout of the transmission, the setting of the area to which the ejected oil flow is applied, including the setting of a plurality of areas on the bearing surface to which the ejected oil flow is applied, suffers from a small degree of freedom. In the generator, since the generating coil to be heated is positioned opposite to the free wheel gear axially across the free wheel, it is difficult to cool the generating coil with the oil supplied to the bearing surface.
The present invention has been made in view of the above drawbacks. It is an object of the present invention to provide a lubricating oil supply structure for an internal combustion engine, which requires no lubricating oil passage to be defined in a crankshaft. In addition, it is an object to provide a lubricating oil supply structure which is capable of ejecting lubricating oil to a lubrication object mounted on a crankshaft opposite to the stator of a generator across a flange of the rotor of the generator in an axial direction, is free of limitations on the layout of the generator and peripheral devices, is capable of cooling generating coils of the generator, and allows the area of the lubrication object to which the lubricating oil is applied to be set with large freedom. It is an object of a second aspect of the present invention to increase the ability to cool the generating coil. It is an object of a third aspect of the present invention to prevent the generator from being large in size. It is an object of a fourth aspect of the present invention to simplify a structure inside a housing member which stores the generator, to allow nozzles to be set in various positions with ease, and to obtain an ejected flow of lubricating oil with high directivity.
According to the first aspect of the present invention, a lubricating oil supply structure for an internal combustion engine includes a generator having a stator with a generating coil and a rotor coupled to a crankshaft. The generator is housed in a housing member, and a lubrication object is mounted on the crankshaft and is disposed opposite to the stator across a flange of the rotor in an axial direction of the crankshaft. Furthermore, the housing member has a nozzle forming region combined with a lubricating oil passage. The nozzle forming region has a first nozzle in communication with the lubricating oil passage for continuously ejecting lubricating oil. The first nozzle is disposed on the stator side in confronting relation to the flange in the axial direction. The rotor has a first through passage disposed at a position confronting the lubrication object in an ejected direction in which the lubricating oil is ejected from the first nozzle, so that the lubricating oil is ejected from the first nozzle through the first through passage to the lubrication object.
Since the first nozzle is provided in the nozzle forming region of the housing member which houses the generator having the rotor rotatable in unison with the crankshaft, the first nozzle and the lubrication object are provided about the crankshaft. Since the lubricating oil is ejected to the rotor from the first nozzle which is disposed on the stator side opposite to the flange and confronts the flange in the axial direction, the lubricating oil is ejected almost in its entirety to the generator reliably. The ejected lubricating oil is supplied to the lubrication object through the first through passage which is positioned intermittently in the ejected flow of lubricating oil depending on the angular position of the rotor. When the first through passage is not positioned in the ejected flow of lubricating oil, the lubricating oil hits the rotor and is scattered. Splashes of the scattered lubricating oil are applied mainly to the side of the generating coil near the flange.
As a result, the first aspect of the present invention offers the following advantages: The housing member has the nozzle forming region combined with the lubricating oil passage, and the nozzle forming region has the first nozzle in communication with the lubricating oil passage for continuously ejecting lubricating oil. Therefore, the first nozzle and the lubrication object are provided about the crankshaft. The lubricating oil is supplied to the lubrication object when it is ejected from the nozzle of the nozzle forming region of the housing member, without the need for forming a lubricating oil passage in the crankshaft. The nozzle does not pose limitations on the layout of the generator and devices disposed around the crankshaft.
The first nozzle is disposed on the stator side in confronting relation to the flange in the axial direction of the crankshaft, and the rotor has the first through passage disposed at a position confronting the lubrication object in the ejected direction in which the lubricating oil is ejected from the first nozzle. Accordingly, the lubricating oil is ejected from the first nozzle positioned near the stator to the rotor. Thus, the lubricating oil is ejected almost in its entirety to the generator reliably, and is ejected to the lubrication object through the first through passage in the rotor which rotates in unison with the crankshaft. Specifically, the lubricating oil continuously ejected from the first nozzle is supplied to the lubrication object through the first through passage which is positioned intermittently in the ejected flow of lubricating oil depending on the angular position of the rotor. When the first through passage is not positioned in the ejected flow of lubricating oil, the lubricating oil hits the rotor and is scattered. Splashes of the scattered lubricating oil are applied mainly to the side of the generating coil near the flange. Consequently, the lubrication object is lubricated by the lubricating oil which has passed through the first through passage, and the generating coil is simultaneously cooled by the scattered lubricating oil, thus increasing the generating efficiency of the generator.
Inasmuch as the first nozzle is provided in the nozzle forming region of the housing member, the position of the first nozzle can be set in the circumferential direction with a large degree of freedom, and the number of first nozzles can be set with a large degree of freedom. Therefore, the area of the lubrication object to which the lubricating oil is applied can be set with a large degree of freedom. The positions and number of first nozzles can be set appropriately from the standpoints of the ability to lubricate the lubrication object and the ability to cool the generator.
According to the second aspect of the present invention, in the lubricating oil supply structure for an internal combustion engine according to the first aspect of the present invention, the nozzle forming region has a second nozzle for continuously ejecting lubricating oil, so that the lubricating oil is ejected from the second nozzle to a side of the generating coil opposite to the flange.
The lubricating oil ejected from the nozzle and applied to and scattered by the rotor is applied mainly to a portion of the generating coil near the flange, and the lubricating oil ejected from the second nozzle is applied to a side of the generating coil which is opposite to the flange in the axial direction (hereinafter referred to as xe2x80x9copposite-to-flange sidexe2x80x9d). The lubricating oil applied to and scattered by this side is applied mainly to the generating coil and nearby generating coils on the opposite-to-flange side.
As a result, the second aspect of the present invention offers the following advantages: Since the second nozzle is provided for ejecting the lubricating oil to the opposite-to-flange side of the generating coil, the generating coil to which the lubricating oil ejected from the second nozzle is directly applied, and the nearby generating coils are cooled by the scattered lubricating oil. In addition, the lubricating oil ejected from the first nozzle is applied to the portion of the generating coil near the flange and cools the generating coil. Accordingly, the generating coil is cooled from axially opposite sides thereof, and hence the ability to cool the generating coil is increased. Inasmuch as the amounts of the lubricating oil ejected respectively from the first nozzle and the second nozzle can be set separately from each other, optimum ejected amounts of the lubricating oil can be set depending on the lubricating and cooling actions of the separately ejected flows of the lubricating oil.
According to the third aspect of the present invention, in the lubricating oil supply structure for an internal combustion engine according to the first and second aspects of the present invention, the stator has a second through passage confronting the first through passage in the ejected direction, so that the lubricating oil is ejected from the first nozzle through the second through passage and the first through passage to the lubrication object.
The flow of the lubricating oil ejected from the nozzle passes through the second through passage defined in the stator. Then, when the second through passage and the first through passage are in an overlapping position in the ejected direction depending on the angular position of the rotor, the ejected flow of the lubricating oil passes through the first through passage and is applied to the lubrication object. When the second through passage and the first through passage are not in an overlapping position in the ejected direction, the ejected flow of the lubricating oil is applied to and scattered by the rotor, and splashes of the lubricating oil are applied to the generating coil.
As a result, the third aspect of the present invention offers the following advantages: Since the stator has the second through passage in confronting relation to the first through passage in the ejected direction, the nozzle and the stator can be placed in an overlapping position in the axial direction. The generator is thus prevented from becoming large in size due to the nozzle.
According to the fourth aspect of the present invention, in the lubricating oil supply structure for an internal combustion engine according to the third aspect of the present invention, the nozzle forming region includes a stator support to which the stator is fixed. The first nozzle is open at an abutment surface held in abutment against the stator. Furthermore, the second through passage includes a through hole having an opening connected to the first nozzle on the abutment surface.
The nozzle forming region is provided by the stator support. Furthermore, the lubricating oil ejected from the first nozzle passes through the second through passage, which is substantially free of the effect of an air flow caused by the rotation of the rotor immediately after the lubricating oil is ejected. The oil then reaches the first through passage.
As a result, the fourth aspect of the present invention offers the following advantages: Since the nozzle forming region includes the stator support, the nozzle forming region is provided by the stator support. Therefore, the nozzle forming region does not need to be provided separately, and the structure in the housing member is simplified. The positions of the first and second nozzles and the number of the first and second nozzles can be set with ease from the standpoints of the ability to lubricate the lubrication object and the ability to cool the generating coil. The second through passage which comprises the through hole has the opening connected to the first nozzle on the abutment surface where the first nozzle is open. Consequently, the lubricating oil ejected from the first nozzle passes through the second through passage, which comprises the through hole which is substantially free of the effect of an air flow caused by the rotation of the rotor immediately after the lubricating oil is ejected. Since the distance over which the lubricating oil is exposed to the air flow is short after the lubricating oil is ejected from the first nozzle until it reaches the first through passage, the directivity of the ejected flow of the lubricating oil is increased. Even when the pressure of the lubricating oil is somewhat low, the ejected flow of the lubricating oil reliably passes through the first through passage and reaches the lubrication object, resulting in an increase in the ability to lubricate the lubrication object.
The terms xe2x80x9caxial directionxe2x80x9d, xe2x80x9cradial directionxe2x80x9d, and xe2x80x9ccircumferential directionxe2x80x9d used in the specification mean the direction of the axis around which the crankshaft rotates, the radial direction extending radially from the axial direction, and the circumferential direction about the axial direction, respectively.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.